JP2009187594A - Method for forming micropattern, and substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for forming a micropattern which can easily form a pattern whose line width is narrower than that of an original for transfer. <P>SOLUTION: One or more concave patterns are formed on a first substrate 3, and a dielectric film 4 is formed on the concave patterns. Thereafter, a first photo setting resin 2 is applied, and a second substrate 5 is bonded on the first photo setting resin 2. Then the first photo setting resin 2 is cured by irradiation with light. After curing, the first substrate 3 is separated from the second substrate 5 at a boundary between the dielectric film 4 and the first photo setting resin 2, and then a convex pattern whose line width is narrower than that of the concave pattern of the first substrate 3 is transferred to the first photo setting resin 2 on the second substrate 5. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fine pattern forming method and a substrate, and more specifically, a fine pattern forming method for forming a convex or concave fine pattern on a substrate by pattern transfer, and a fine pattern formed by such a forming method. It is related with the board | substrate which has.

  With the rapid development of the digital information society in recent years, there has been a demand for an increase in capacity of an optical disk, which is a typical storage device, and development is being vigorously promoted in various places. The optical disc of φ120 mm that is currently commercialized has a pit length of 0.1 μm to 0.2 μm and a capacity of about 15 GB to 30 GB. In next-generation and next-generation optical discs, attempts have been made to increase the capacity by further shortening the shortest pit length.

  In the next-generation and next-generation optical discs, a master disc is manufactured using a Deep UV laser beam or an electron beam. It has been reported that when the master is produced using Deep UV laser light, very short pits having a shortest pit length of 80 nm and an electron beam of about 40 nm can be formed. When the shortest pit length is about 40 nm, the capacity is estimated to be about 500 GB / 12 cm. An optical disk substrate used for high-density recording / reproduction is manufactured by an injection molding method using the above-described optical disk master.

  As another method for narrowing the groove width of the optical disk substrate, there is a method described in Patent Document 1. In Patent Document 1, a sidewall is provided in a groove portion of an optical disk master, and Ni plating is performed based on the sidewall, thereby producing an optical disk substrate having a narrower groove portion by injection molding.

  Also, as a candidate for increasing the capacity of HDDs, the development of patterned media aiming at 1 Tbit / square inch or more, which is 10 times the current recording density of 100 Gbit / square inch, has been energetically promoted. In order to realize 1 Tbit / square inch, it is necessary to set the dot interval to 25 nm or less, and it is necessary to arrange the dots in a line in the circumferential direction. In order to realize this, a concave / convex pattern similar to the land / groove pattern provided on the optical disk is formed on the Al layer on the magnetic disk substrate, and then anodization is performed so that minute dots are formed only on the groove portion. Regularly arranged techniques have been developed.

  Furthermore, in semiconductors and TFT devices, with the aim of high integration and high speed and low power consumption, the gate length and the source and drain electrodes have been intensively researched and developed.

  In order to increase the recording density of optical disks and HDD media as described above, and to reduce the gate length of semiconductors and TFT elements, how to reduce the pattern size of the original master and photomask Realization is the key. For miniaturization, a pattern that has been miniaturized to the limit by deep UV exposure or electron beam exposure is formed.

Further, unlike the nano-level fine patterns as described above, fine patterns in units of microns or sub-microns are mainly used in optical waveguides typified by optical communication devices. In the optical waveguide, a buried polymer optical waveguide wafer is manufactured. After a master having a desired optical waveguide shape is manufactured, a fine pattern is formed on the Si wafer.
JP 2002-342987 A

  However, the conventional techniques described above have the following problems. That is, when producing a master disk for manufacturing an optical disk or HDD substrate, or a photomask such as a semiconductor or TFT, the minimum dimensions of the master, such as the track width, track pitch, or pit shape, or the gate of a semiconductor or TFT, etc. The minimum line width of the photomask that defines the length is determined by the performance of the exposure apparatus used. Since it is impossible to form a fine pattern below the performance of the exposure machine to be used, it is difficult to perform further miniaturization.

  In general, the substrate of the optical disk is produced by injection molding using the above-mentioned master, but when a nano-level fine pattern is formed by injection molding, depending on the molding conditions, it is drawn with an electron beam or the like. In addition, it has been confirmed that a fine pattern shape cannot be faithfully reproduced and a problem that desired substrate characteristics cannot be obtained occurs. Furthermore, it is difficult to easily produce a pattern with a relatively narrow line width, such as an optical waveguide, that is smaller than the line width engraved on the master, and fine adjustment of the pattern width can be easily performed. However, there is also a problem that it is difficult to shorten the manufacturing process because it is necessary to prepare the master again.

  In Cited Document 1, a dielectric film such as SiN is formed on the glass master, and the entire surface is etched back by RIE to form sidewalls, and the excess formed on the bottom and convex portions of the concave portion of the glass master. The thin film is removed, leaving only the sidewalls, and narrowing the groove width of the recesses. In Cited Document 1, if the excess film formed on the bottom and convex portions of the concave portion of the glass master is etched back by RIE, the following problems occur.

  It is very difficult to uniformly etch back a large-diameter glass master used for an optical disk by RIE, and it is difficult to accurately control the remaining film thickness of the sidewall that defines the groove width. In addition, the bottom and convex portions of the concave portion of the glass master disk cannot be etched back uniformly due to the influence of the wall formed perpendicular to the concave portion. The film formed on the bottom is not completely removed, and the film remains, making it difficult to obtain a glass master having a desired depth. Furthermore, since it is difficult to accurately control the end point during etch back, overetching may occur, and it is very difficult to obtain a desired shape with good reproducibility. In addition, as described above, when a desired glass master cannot be obtained by overetching or the like in the RIE process, it is necessary to start again from the first resist process, which is very time consuming.

  The present invention solves the above-mentioned problems, and can easily form a pattern having a line width narrower than the line width of a pattern to be transferred, and a fine pattern formed by such a forming method. It aims at providing the board | substrate which has this.

  In order to achieve the above object, the fine pattern forming method of the present invention includes a step of forming a dielectric film on a first substrate on which one or more concave patterns are formed, and a first step on the dielectric film. Applying the photocurable resin, bonding the second substrate onto the first photocurable resin, curing the first photocurable resin by light irradiation, and the first Separating the substrate and the second substrate at the boundary between the dielectric film and the first photocurable resin, and on the first photocurable resin, more than the concave pattern. A convex pattern having a narrow line width is transferred.

  The substrate of the present invention has a fine pattern formed by the fine pattern forming method of the present invention.

  In the fine pattern forming method of the present invention, it is possible to easily form a pattern having a line width narrower than the line width of the pattern to be transferred.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. 1A to 1I show a process of creating a fine pattern created by the fine pattern forming method of one embodiment of the present invention. Creation of a fine pattern is roughly divided into a step of creating a concave pattern from a convex pattern formed on the master (FIGS. 1A to 1D), and a convex pattern having a narrower line width than the concave pattern. There are three steps: a step of creating a pattern (FIGS. 1D to 1G) and a step of creating a concave pattern from a convex pattern having a narrow line width (FIGS. 1G to 1I). The created fine pattern can be used for fine processing of storage devices, optical devices, biodevices, semiconductor devices, and the like. Hereinafter, it will be described how the pattern shape and the pattern width of a part of the first fine pattern formed on the master changes depending on the process.

  A convex first fine pattern 10 exposed and developed by an electron beam exposure apparatus is formed on the master mold 1 (FIG. 1A). A first photocurable resin 2 containing fluorine is applied onto the master mold 1 (FIG. 1B) and bonded to the first substrate 3 (FIG. 1C). Thereafter, ultraviolet rays are irradiated from the outside through the first substrate 3 to cure the first photocurable resin 2. After the ultraviolet irradiation, the master mold 1 and the first substrate 3 are separated (FIG. 1D). The primary mold 110 in which the second fine pattern 11 having the same pattern shape and pattern width as the first fine pattern 10 formed on the master mold 1 is formed on the first substrate 3 by the steps so far. Can be obtained. The second fine pattern 11 is a concave pattern having a concave and convex direction opposite to that of the first fine pattern 10.

  In the above description, the primary mold 110 is obtained from the master mold 1 by pattern transfer. However, the formation of the primary mold is not limited to this. For example, a second fine pattern (concave pattern) may be formed by injection molding on a PC (polycarbonate) substrate, and this may be used as a primary mold.

Next, using the primary mold 110, a pattern having the same pattern shape as the second fine pattern 11 and a line width narrower than that of the second fine pattern 11 is created. A dielectric film 4 is formed on the primary mold 110 (FIG. 1E). As the dielectric film 4, for example, a SiO ₂ film is formed with a thickness of 25 nm. By forming the dielectric film 4 on the primary mold 110, the second fine pattern 11, which is a concave pattern formed on the primary mold 110, is compared with the pattern before the dielectric film 4 is formed. The width becomes narrower.

  After the formation of the dielectric film 4, the fluorine-containing first photocurable resin 2 is applied on the primary mold 110 and bonded to the second substrate 5 (FIG. 1F). After bonding, ultraviolet rays are irradiated from the outside through the second substrate 5 to cure the first photocurable resin 2. After curing, the primary mold 110 and the second substrate 5 are separated (FIG. 1G). By separating the second substrate 5, the second fine pattern 11 formed on the primary mold 110 is transferred onto the first photocurable resin 2 laminated on the second substrate 5, A convex third fine pattern 12 can be obtained. The third fine pattern 12 has the same convex shape as the first fine pattern 10 formed on the master mold 1, but the pattern width is narrower than that of the first fine pattern 10. It is a pattern.

  Subsequently, the convex third fine pattern 12 formed on the second substrate 5 is used as the secondary mold 120, and the fine pattern of the secondary mold 120 is transferred and formed. Unlike the first photocurable resin, the second photocurable resin 7 containing no fluorine is applied on the secondary mold 120 on which the convex third fine pattern 12 is formed, Adhering to the substrate 6 is performed (FIG. 1H). Then, after irradiating an ultraviolet-ray from the outside and hardening the 2nd photocurable resin 7, the secondary mold 120 and the 3rd board | substrate 6 are isolate | separated (FIG. 1I). By doing in this way, the 3rd fine pattern 12 formed on the secondary mold 120 is transcribe | transferred on the 2nd photocurable resin 7 laminated | stacked on the 3rd board | substrate 6, and 1st A concave fourth fine pattern 13 having a line width narrower than that of the fine pattern 10 is obtained. The pattern shape of the fourth fine pattern 13 is a reverse pattern of the convex first fine pattern 10 (FIG. 1A) on the master mold 1.

  2A to 2C show the line width (pattern width) of each fine pattern. The secondary mold 120 is obtained by transfer from a pattern in which the dielectric film 4 is formed on a concave pattern having the same line width as that of the first fine pattern 10 (FIG. 2A) on the master mold 1. For this reason, the line width of the 3rd fine pattern 12 formed on the secondary mold 120 becomes narrower than the line width of the 1st fine pattern 10 (FIG.2 (b)). Further, since the fourth fine pattern 13 is an inverted pattern of the third fine pattern, the line width of the fourth fine pattern 13 is the same as the line width of the third fine pattern. This is narrower than the line width of the fine pattern 10 (FIG. 2C).

  In the present embodiment, the dielectric film 4 is formed on the first substrate 3 on which one or more concave patterns (second fine patterns 11) are formed, and the first photocurable resin is formed on the dielectric film 4. 2 is applied and the second substrate 5 is bonded, and then the first photocurable resin 2 is cured. Thereafter, the first substrate 3 and the second substrate 5 are separated at the boundary between the dielectric film 4 and the first photocurable resin 2, so that the first photocurable resin 2 is A convex pattern (third fine pattern 12) having a narrower line width than the concave pattern formed on one substrate 3 is transferred. By doing in this way, it has a pattern whose line width is narrower than the convex pattern (first fine pattern 10) formed in the master mold 1 used when forming the concave pattern on the first substrate 3. The second master (secondary mold 120) can be easily obtained. In addition, since the line width of the third fine pattern 12 can be controlled by controlling the film thickness of the dielectric film 4, fine adjustment of the line width can be easily performed.

  In the present embodiment, the second photocurable resin 7 is applied on the secondary mold 120 created above, and the third substrate 6 is bonded together, and then the second photocurable resin is cured. Then, the second photocurable resin 7 is separated from the second substrate 5 and the third substrate 6 at the boundary between the first photocurable resin 2 and the second photocurable resin 7. A concave pattern (fourth fine pattern 13) corresponding to the convex pattern formed on the secondary mold 120 is transferred onto the top. Since the concave pattern (fourth fine pattern 13) formed in this way has the same line width as the third fine pattern 12, the line width is larger than that of the first fine pattern 10 formed on the master mold 1. A narrow concave fourth fine pattern can be formed.

  The third fine pattern 12 and the fourth fine pattern 13 can be used for patterning a substrate or the like. In this case, since it is not necessary to use an expensive master for patterning the substrate, the life of the master can be extended and the master can be used repeatedly, so that the cost of the product can be reduced.

  In the above, a convex third fine pattern 12 having a narrow line width is formed from the concave second fine pattern 11, and a concave fourth pattern having the same line width is formed from the convex third fine pattern 12. The fine pattern 13 is formed. By using the same process as that for forming the third fine pattern 12 from the second fine pattern 11, the fourth fine pattern 13 is changed from the concave fourth fine pattern 13. Alternatively, another convex pattern having a narrower line width can be formed. That is, a dielectric film is formed on the concave fourth fine pattern 13, a first photocurable resin is applied, and another substrate is attached thereon, and then the first photocurable property is obtained. The resin is cured and the substrate is separated. By doing so, a convex pattern having a narrower line width than the fourth fine pattern 13 can be obtained. In addition, by applying a process similar to that for forming the concave fourth fine pattern 13 from the convex third fine pattern 12 to the convex pattern thus obtained, the fourth pattern A concave pattern having a narrower line width than the fine pattern 13 can be obtained.

In this embodiment, at the time of pattern transfer, the fluorine-containing first photocurable resin 2 is used in FIGS. 1C and 1F, and the fluorine-free second photocurable resin 7 is used in FIG. 1H. The reason why these are properly used is that FIGS. 1C, 1F, and 1H differ in the material of the lower layer (pattern) when the photocurable resin is applied. That is, Ni, Si, SiO ₂ or the like is generally used as a material for the master mold 1 (FIG. 1C). The master mold 1 is formed with a first fine pattern 10 produced using an electron beam exposure apparatus, a Deep-UV exposure apparatus, or the like. That is, the first fine pattern 10 is made of Ni, Si, SiO ₂ or the like. In this case, when the first fine pattern 10 is transferred to the surface of another substrate, if a photocurable resin not containing fluorine is used, the master and the substrate for pattern transfer are obtained after UV curing for pattern transfer. Cannot be separated cleanly, resulting in pattern destruction and damage to the master. This is due to the high adhesiveness of the photocurable resin not containing fluorine to the material of the master. On the other hand, the first photo-curing resin containing fluorine has a contact angle of water of 100 degrees or more on the surface after UV curing, so that the separation from the master is good and the pattern transfer can be performed smoothly. it can.

In FIG. 1F, a dielectric film 4 is formed on the concave pattern, and a fluorine-containing first photocurable resin 2 is applied thereon. If pattern transfer is performed by applying a fluorine-containing photocurable resin directly on the concave pattern formed of the fluorine-containing first photocurable resin 2 and irradiating it with ultraviolet rays or the like to cure it. Then, sticking occurs at the pattern boundaries, and pattern separation for transfer cannot be performed. The same applies to the case where a concave pattern on a PC board that is replicated in large quantities by injection molding is used as the concave pattern. In this embodiment, since the dielectric film 4 is formed on the concave pattern, the fluorine-containing first photocuring is performed even when the concave pattern is formed of a material other than Ni, Si, or SiO _2. Resin 2 is used. A smooth pattern transfer can be obtained by forming a dielectric film 4 such as SiO ₂ on the concave pattern, and applying and curing the fluorine-containing first photocurable resin 2 on the concave film. . At the same time, by laminating the dielectric film 4 described above, the groove width of the concave portion is reduced, and a convex pattern having a pattern width narrower than the groove width of the original concave portion can be easily obtained. Further, by forming the dielectric film 4 in a concave shape uniformly, the step of removing the unnecessary portion of the film by etching back processing such as RIE becomes unnecessary, and a substrate having a narrower pattern width can be formed by a simple process. Can be easily obtained.

  On the other hand, when transferring the convex pattern formed on the secondary mold (FIG. 1H), the second photocurable resin 7 not containing fluorine is used. This is because the third fine pattern 12 (FIG. 1G) formed on the second substrate 5 is formed of the first photocurable resin 2 containing fluorine, and thus does not contain fluorine. This is because even when the second photocurable resin 7 is applied and cured, the substrates can be separated without any problem and pattern transfer is possible. In addition, when using a fluorine-containing first photocurable resin, surface treatment is required on the surface of the substrate to be bonded to enhance the adhesion with the first photocurable resin, but fluorine is included. In the case where the second photo-curing resin is used, the surface of the substrate to be used does not require any surface treatment to increase the adhesion, and the process is simple.

  As described above, in accordance with the type of material forming the substrate on which pattern transfer is to be performed, by using a photocurable resin that allows easy pattern separation with the material, drawing is performed with an electron beam or the like. In addition, a pattern that faithfully reproduces the fine pattern of the transfer source can be obtained, and desired substrate characteristics can be easily obtained. Further, when a pattern on a PC substrate replicated by injection formation is used as a transfer source fine pattern at the time of pattern transfer, the PC substrate corresponds to the second master. Since this second master can be replicated in large quantities by injection molding, another master can be prepared immediately even when the formation of the dielectric film or the pattern separation is hindered. Therefore, it is possible to easily transfer and form a fine pattern. Further, in such a case, the Ni master for injection molding produced over a long period of time can be used again for injection molding, leading to a longer life of the Ni master and consequently to a reduction in manufacturing cost.

  Hereinafter, description will be made using examples. First, the first embodiment will be described. The first embodiment uses a Si master mold in which a fine pattern with a pattern width of 100 nm formed by an electron beam exposure apparatus is used, and has a narrower pattern width than the pattern width of this master mold. A mold is formed, and then the fine pattern is transferred using the secondary mold. Here, for convenience, a case where a convex pattern is formed on the master mold 1 will be described (FIG. 1A).

  First, a fluorine-containing first photocurable resin 2 is applied and developed on an Si master disc mold 1 produced by an electron beam exposure apparatus (FIG. 1B). The fluorine-containing first photocurable resin 2 includes fluorine-containing monomers: 25 wt%, tetraethylene glycol diacrylate: 35 wt%, 2-methyl-2-adamantyl acrylate: 35 wt%, surfactant: 1 wt%, And photopolymerization initiator: A photocurable resin composed of 4 wt% was used. The fluorine-containing first photocurable resin 2 was applied on the Si master mold 1 and developed, and then bonded to the first substrate 3 (FIG. 1C). The first substrate 3 is subjected to a surface treatment that enhances the adhesion between the fluorine-containing first photocurable resin 2. In general, silane coupling treatment is used for this surface treatment.

After bonding the substrates, ultraviolet rays were irradiated from the first substrate 3 side. The exposure amount of ultraviolet rays was 5 J / cm ² and the exposure time was 15 sec. After the ultraviolet irradiation, the master mold 1 and the first substrate 3 were separated (FIG. 1D). At this time, the fluorine-containing first photocurable resin 2 was separated in a state in which the unevenness of the master mold 1 was faithfully reflected and adhered to the first substrate 3 side. This is because the contact angle of water on the surface after ultraviolet curing of the fluorine-containing first photocurable resin 2 is 100 degrees or more, so that the separation from the master is good, and the surface of the first substrate 3 is This is because the surface treatment is performed in advance, so that the adhesion between the surface of the first substrate 3 and the first photocurable resin 2 containing fluorine is high.

  On the surface of the first substrate 3 after the substrate separation, a layer of the fluorine-containing first photocurable resin 2 to which the concave pattern is transferred is formed. The transferred concave pattern is an inverted pattern of the convex pattern on the master mold 1, and the pattern width is the same as the pattern width of the first fine pattern 10 on the master mold 1. This concave pattern is referred to as a second fine pattern 11, and the second fine pattern 11 and the first substrate 3 are referred to as a primary mold 110 (FIG. 1D).

  Subsequently, a convex pattern is formed using the primary mold 110 on which the second fine pattern 11 is formed. First, a SiON film was formed as the dielectric film 4 with a thickness of 25 nm on the second fine pattern 11 (FIG. 1E). Next, the fluorine-containing first photocurable resin 2 was applied and spread, and then the second substrate 5 was bonded (FIG. 1F) and irradiated with ultraviolet rays. The ultraviolet irradiation conditions are the same as those described above. When the first substrate 3 and the second substrate 5 are separated after the ultraviolet irradiation, a convex pattern formed of the fluorine-containing first photocurable resin 2 is formed on the second substrate 5. . This convex pattern is referred to as a third fine pattern 12, and the third fine pattern 12 and the second substrate 5 are referred to as a secondary mold 120 (FIG. 1G).

  The third fine pattern 12 (FIG. 2B) transferred onto the second substrate 5 is convex as in the first fine pattern 10 formed on the master mold 1 (FIG. 2A). Type pattern. The line width of the third fine pattern 12 is narrower than the line width of the first fine pattern 10. As a result of measuring the line width of the transferred third fine pattern 12, the pattern width was 48 nm. Since the pattern width of the first fine pattern 10 formed on the master mold 1 is 100 nm, it is possible to form a pattern having a pattern width of about ½ of the pattern width. From the above, it was confirmed that the secondary mold 120 having a narrower pattern width than the pattern width on the master mold 1 manufactured by the electron beam exposure apparatus can be obtained.

Next, a second embodiment will be described. In this example, a concave pattern having the same pattern shape and pattern width as the secondary mold 120 is formed using the secondary mold 120 (FIG. 1G) created in the first example. On the secondary mold 120, the second photocurable resin 7 containing no fluorine was applied and developed, and then bonded to the third substrate 6 (FIG. 1H). As the fluorine-free second photocurable resin 7, an ultraviolet curable resin mainly composed of an acrylate ester was used. Thereafter, ultraviolet irradiation was performed through the third substrate 6 to separate the secondary mold 120 and the third substrate 6. The exposure amount of ultraviolet rays was 6 J / cm ² and the exposure time was 18 sec.

  On the surface of the third substrate 6, a fourth fine pattern 13 formed of the fluorine-free second photocurable resin 7 was formed (FIG. 1I). The pattern width of the transferred fourth fine pattern 13 is the same as the pattern width of the third fine pattern 12 formed on the secondary mold 120, but the direction of the unevenness is reversed. Actually, when the pattern width of the transferred fourth fine pattern 13 was measured, the pattern width was 47.6 nm. This is almost equivalent to the pattern width 48 nm of the third fine pattern 12. A possible reason for the inconsistency is that the second photocurable resin 7 is cured and contracted when transferred using the third fine pattern 12.

  As described in the first embodiment, the convex third fine pattern 12 (FIG. 2B) transferred onto the second substrate 5 is formed on the master mold 1 (FIG. 2A). The pattern width is narrower than the formed convex first fine pattern 10. Using the third fine pattern 12, a concave fourth fine pattern 13 having the same pattern shape and pattern width as the third fine pattern 12 can be formed (FIG. 2C).

  From the above, it can be seen that by using the process shown in FIGS. 1A to 1I, a pattern with a narrower pattern width and its inverted pattern can be easily formed based on the fine pattern created by the electronic exposure apparatus. . This indicates that an extremely uneven pattern having a narrower pattern width can be formed using an extremely fine pattern formed by an electronic exposure apparatus. Therefore, it is possible to miniaturize an isolated pattern that defines a gate length of a semiconductor or the like and a recording or reproducing track width of a magnetic head.

  Here, the relationship between the film thickness of the dielectric film 4 laminated on the second fine pattern 11 and the pattern width of the third fine pattern 12 will be described. FIG. 3 shows the relationship between the film thickness of the dielectric film 4 and the pattern width of the third fine pattern 12. Here, the pattern width of the second fine pattern 11 is 200 nm. Referring to FIG. 3, it can be seen that the pattern width of the transferred third fine pattern 12 monotonously decreases as the thickness of the dielectric film 4 laminated on the second fine pattern 11 increases. Since the pattern width to be transferred depends on the initial pattern width for forming the dielectric film 4 and the film thickness of the dielectric film 4, the pattern width to be used in advance (here, the second width, which is the starting point) It is desirable to proceed the transfer process after grasping the relationship between the pattern width of the fine pattern 11) and the thickness of the laminated film of the dielectric film 4.

  The dielectric film 4 for adjusting the pattern width is preferably selected from the group consisting of oxides, nitrides and oxynitrides having an extinction coefficient of 0.1 or less. The reason will be described below. As shown in FIGS. 1E to 1F, the dielectric film 4 for adjusting the pattern width is formed on the second fine pattern 11 on the first substrate 3, and the fluorine-containing first film is formed thereon. After the photocurable resin 2 is applied and spread, it is bonded to the second substrate 5 and irradiated with ultraviolet rays from the outside. At that time, when either the first substrate 3 or the second substrate 5 is transparent, ultraviolet rays are irradiated through the transparent substrate. The irradiated ultraviolet rays are absorbed by the fluorine-containing first photocurable resin 2 and the resin is cured.

Consider a case where the second substrate 5 is made of a material such as metal or Si. In that case, it is necessary to irradiate ultraviolet rays from the first substrate 3 side. At that time, when the ultraviolet absorption in the dielectric film 4 is large, the irradiated ultraviolet light is absorbed by the dielectric film 4, and the ultraviolet light does not reach the fluorine-containing first photocurable resin 2 sufficiently. The material does not cure well. The extinction coefficient of the film was adjusted by changing the film formation conditions of the dielectric film 4, and actually the hardness of the surface of the ultraviolet curable resin when ultraviolet light was irradiated through the dielectric film was measured. Table 1 shows the relationship between the extinction coefficient of the dielectric film and the pencil hardness.

  Referring to Table 1, it can be seen that when the extinction coefficient is smaller than 0.2, the hardness is 2H or more and curing is performed. The first photo-curable resin 2 desirably has a hardness of 3H, and an extinction coefficient of 0.1 or less is desirable. As the dielectric film 4 having an extinction coefficient of 0.1 or less, oxides such as Si, Al, Ta, Ni, Zr, and Zn, nitrides, or oxynitrides can be widely used.

  A third embodiment will be described. In the third embodiment, a PC substrate to which a fine pattern is transferred by injection molding, which is generally used as an optical disk molding substrate, is used as the primary mold 110. Usually, a PC substrate onto which a fine pattern has been transferred is produced in large quantities by injection molding using a molding machine based on a Ni master mold. Using this Ni master mold, a fine pattern can be transferred by the same process as in the first and second embodiments. However, when an ultraviolet curable resin adheres to the Ni master mold for some reason, the expensive Ni master mold becomes unusable thereafter. In order to avoid this, a fine pattern is transferred by a transfer process shown below using a PC substrate manufactured in units of several thousand sheets from one Ni master mold. By doing in this way, the board | substrate which has a fine pattern can be replicated in large quantities, without damaging expensive Ni original disc mold.

  In this embodiment, a ROM substrate on which pits are formed will be described. 4A to 4H show the process of creating the ROM substrate. A fifth fine pattern 14 is formed on the Ni master 20 for molding a PC substrate used as a primary mold (FIG. 4A). A sixth fine pattern 15 was formed on the PC substrate 100 using the Ni master 20 (FIG. 4B). This PC board 100 is used as a primary mold 110. The pit shape (sixth fine pattern 15) formed on the PC substrate 100 was pit length = 200 nm, pit width = 180 nm, and pit depth = 60 nm.

A dielectric layer 40, which is a SiO ₂ film, was formed on the PC substrate 100 at a thickness of 20 nm (FIG. 4C). After the formation of the dielectric layer 40, the fluorine-containing first photocurable resin 2 is applied on the PC substrate 100, spread, and bonded to the fourth substrate 8, and then the first photocurable resin is applied. 2 was irradiated with ultraviolet rays through the fourth substrate 8 (FIG. 4D). Fluorine-containing first photocurable resin 2 includes fluorine-containing monomers: 25 wt%, tetraethylene glycol diacrylate: 35 wt%, 2-methyl-2-adamantyl acrylate: 35 wt%, surfactant: 1 wt% and Photopolymerization initiator: A photocurable resin composed of 4 wt% was used. The exposure amount of ultraviolet rays was 5 J / cm ² and the exposure time was 15 seconds. After the ultraviolet irradiation, the PC substrate 100 and the fourth substrate 8 were separated to obtain a seventh fine pattern 16 (FIG. 4E).

Next, after applying and developing the fluorine-free second photocurable resin 7 on the seventh fine pattern 16 formed on the fourth substrate 8 (FIG. 4F), the fifth substrate 9 and irradiated with ultraviolet rays through the fifth substrate 9 (FIG. 4G). As the fluorine-free second photocurable resin 7, an ultraviolet curable resin mainly composed of an acrylate ester was used. The exposure amount of ultraviolet rays was 6 J / cm ² and the exposure time was 18 sec. After the ultraviolet irradiation, the fourth substrate 8 and the fifth substrate 9 were separated to obtain an eighth fine pattern 17 formed of the second photocurable resin (FIG. 4H).

  The pit shape (eighth fine pattern 17) formed on the fifth substrate 9 was pit length = 170 nm, pit width = 150 nm, and pit depth = 60 nm. When this is compared with the pit shape (FIG. 4B) formed on the primary mold 110, it can be seen that the pit shape is reduced by about 15%. When the pit shape at the starting point (sixth fine pattern 15 in FIG. 4B) is the shortest pit, it is worth 15 GB in the HD DVD format. On the other hand, through the above process, the shortest pit length is reduced by 15%, so that the capacity is increased to 17.2 GB in terms of capacity. As a result of forming a metal reflective film on the actually produced eighth fine pattern 17 and reproducing it, it was confirmed that PRSNR, which is one of the performance indexes, shows a good value of about 22.

  By performing the process described above, not only miniaturization of the isolated pattern that defines the gate length of a semiconductor or the like, or the track width of the recording or reproducing portion of the magnetic head, but also random fine pits such as an optical disk are formed. Even in a fine pattern, the pattern can be further miniaturized, the gate length and the track width of the magnetic sensor can be miniaturized, and the capacity of the optical disk can be increased. Also in the formation of a magnetic disk substrate having a discrete track in which a groove pattern similar to that of an optical disk is formed, the capacity can be increased by applying the above-described process.

  Note that the fine pattern manufacturing process described above is not limited to the above. As described above, it is possible to form a finer pattern by repeatedly performing the process.

  As described above, the present invention has been described based on the preferred embodiments. However, the fine pattern forming method and the substrate of the present invention are not limited to the above embodiments, and various modifications and changes can be made to the configuration of the above embodiments. Changes are also included in the scope of the present invention.

Sectional drawing which shows the original disc mold used for preparation of a primary mold. Sectional drawing which shows the creation process of a primary mold. Sectional drawing which shows the creation process of a primary mold. Sectional drawing which shows a primary mold. Sectional drawing which shows the creation process of a secondary mold. Sectional drawing which shows the creation process of a secondary mold. Sectional drawing which shows a secondary mold. Sectional drawing which shows the creation process at the time of forming a fine pattern using a secondary mold. Sectional drawing which shows the produced fine pattern. (A) is sectional drawing which shows a master mold, (b) is sectional drawing which shows a secondary mold, (c) is sectional drawing which shows the fine pattern formed using the secondary mold. The graph which shows the relationship between the film thickness of a dielectric material film, and the pattern width of the fine pattern formed. Sectional drawing which shows a master. Sectional drawing which shows a primary mold. Sectional drawing which shows the creation process of a secondary mold. Sectional drawing which shows the creation process of a secondary mold. Sectional drawing which shows a secondary mold. Sectional drawing which shows the creation process at the time of forming a fine pattern using a secondary mold. Sectional drawing which shows the creation process at the time of forming a fine pattern using a secondary mold. Sectional drawing which shows the produced fine pattern.

Explanation of symbols

1: Master mold 2: First photocurable resin 3: First substrate 4: Dielectric film 5: Second substrate 6: Third substrate 7: Second photocurable resin 8: Fourth Substrate 9: Fifth substrate 10-17: Fine pattern 20: Ni master 40: Dielectric layer 100: PC substrate 110: Primary mold 120: Secondary mold

Claims (10)

Forming a dielectric film on the first substrate on which the one or more concave patterns are formed;
Applying a first photocurable resin on the dielectric film;
Bonding the second substrate on the first photocurable resin and curing the first photocurable resin by light irradiation; and
Separating the first substrate and the second substrate at the boundary between the dielectric film and the first photocurable resin,
A fine pattern forming method of transferring a convex pattern having a narrower line width than the concave pattern onto the first photocurable resin. Applying a second photocurable resin different from the first photocurable resin on the convex pattern transferred to the first photocurable resin;
Laminating a third substrate on the second photocurable resin, curing the second photocurable resin by light irradiation,
Further separating the second substrate and the third substrate at the boundary between the first photocurable resin and the second photocurable resin,
The fine pattern according to claim 1, wherein a concave pattern having the same line width as the convex pattern transferred onto the first photocurable resin of the second substrate is transferred onto the second photocurable resin. Pattern forming method. Forming a dielectric film on the concave pattern transferred to the second photocurable resin on the third substrate;
Applying a first photocurable resin on the dielectric film;
Bonding the fourth substrate on the first photocurable resin and curing the first photocurable resin by light irradiation; and
Separating the third substrate and the fourth substrate at the boundary between the dielectric film and the first photocurable resin,
The convex pattern having a narrower line width than the concave pattern transferred to the second photocurable resin is transferred onto the first photocurable resin on the fourth substrate. Fine pattern forming method.   The fine pattern forming method according to any one of claims 1 to 3, wherein the first photocurable resin is a fluorine-containing photocurable resin.   The fine pattern forming method according to claim 2, wherein the second photocurable resin is a photocurable resin containing no fluorine.   Prior to the step of forming the dielectric film on the first substrate, a photocurable resin is applied on the substrate on which one or more convex patterns are formed, and the first curable resin is applied on the photocurable resin. One substrate is bonded, the photocurable resin is cured by light irradiation, the substrate on which the convex pattern is formed and the first substrate are separated, and the concave pattern is formed on the first substrate. The fine pattern forming method according to claim 1, further comprising a forming step.   The fine pattern forming method according to claim 6, wherein the substrate on which the convex pattern is formed is formed of a material including one of Ni, Si, and SiO 2.   6. The fine pattern forming method according to claim 1, wherein the first substrate is a PC (polycarbonate) substrate on which the concave pattern is formed by an injection molding method.   The dielectric film is composed of any one or more dielectric films selected from the group consisting of oxides, nitrides, and oxynitrides having an extinction coefficient of 0.1 or less. The fine pattern formation method as described in any one of thru | or 8.   The board | substrate which has a fine pattern formed by the fine pattern formation method as described in any one of Claims 1 thru | or 9.

Images